A test system for rapid screening of patients prior to initiation of thrombolytic therapy will be developed. This system will be based on a novel dry reagent assay technology which recently has been applied successfully to PT and activated PTT tests. Introduction of a rapid convenient test of patient (or clot) lytic potential for use on a decentralized basis could provide early indication of likelihood of success with streptokinase sooner than existing laboratory methods and could serve as an important diagnostic guide in thrombolytic therapy. We propose to develop this test system and to assess its potential using a combination of laboratory studies and clinical sample studies. Application to early determination of clot lysis response in patients prior to thrombolytic therapy will be explored. This work will be performed in conjunction with investigators at University of North Carolina at Chapel Hill. Phase I support would fund assay optimization activities and clinical sample feasibility studies.